Electric fire-alarm and thermo-indicator.



No. 891,948. PATENTED JUNE 30; 1908.

A. H. MONEIL. I ELECTRIC FIRE ALARM AND THERMO INDICATOR.

APPLICATION FILED NOV.11, 1907.

2 SHEET$SHEET l.

No. 891,948. PATENTED JUNE so, 1908 A. H. MQNEIL.

ELECTRIC FIRE ALARM-AND .THERMO INDICATOR.

APPLICATION FILED NQV.11, 1907.

2 SHEETS-SHEET 2.

wfizesses.

UNITED STATES PATENT oFFroE.

nllbltlll) ll EN lt Y .\lt Nl'llil1, OF lllittllkllh PA ltli. ENG LAND.

ELECTRIC FIRE-ALARM AND THERMC-INDICATOR.

Application filed Noxgember 11, 1907.

Specification of Letters Patent.

Patented June 30, 1908.

Serial No. 401,707.

] act description of the invention, such as will.

enable others skilled in the art to which it appertains to make and use the same.

This invention relates to electric fire alarms and tlic'rmo-indicators ot the kind wherein electric contacts are closed by the action ol metal strips which are fixed at both ends and deflected towards the contacts or towards operating devices connected therewith to complete an electric circuit when an :0 abnormal rise of tenmerature occurs. Hitherto in apparatus of this type it has been the practice to employ a single metal strip adapted to press a movable contact against a fixed contact screw adjustable by means of a pointer moving over a suitably graduated dial.

N ow according to this invention two metal strips are employed, and two movable contacts each operatively connected with one of the strips, but both arranged to move in the same path and in the same direction. One of the thermal strips is made more sensitive to changes of temperature than the other strip, and its contact is so arranged behind that actuated by the less sensitive strip, that under normal changes of temperature the two contacts move in the same direction without coming together, but on a sudden rise in the temperature being produccd, the contact operated by the more sensitive strip will move at a quicker rate than the contact in front of it and bear against the slower moving contact thus com-" plcting the alarm circuit. In order to insure 5 that the alarm shall also act even on a gradual rise of temperature should such temper ature exceed a predetermined limit, a stop is provided to arrest the leading contact when such limit is reached to allow the other contact to overtake it and complete the circuit. The stop may also form an electrical contact and close the circuit when the leading movable contactbears against it.

In one way of carrying the invention into practice the two thermal strips are arranged side by side and fixed at their ends to pro 7 electrical contacts are inclosed.

jections on a. base box. One of the strips is made less sensitive than the other by forming it of thicker'metal and eachstrip has a plunger attached to it at or near the middle of its length, which passes through a. hole, gland or 'llexible diapln'agm into the box. lhe-contacts are supported onan insulating base fixed in the box and comprise llat springs arranged in the paths of the plungers which have insulated ends. ()ne of the springs carries an adjusting screw and a dial and moves in front of the other contact .which is on the end of the other spring.

The s rin carrvin the leadin c'ontaetis h o b "O operated by the plunger of the less sensitive thermal strip, and an adjustable fixed stop is provided to limit the motionof this contact as predetermined.

In the accompanying drawings Figure l is affront view eta thermally operated contact apparatus constructed according-to thisin vention, Fig. .Z'is a longitudinal Stt'llflll, and Fig. 3 is a back view with the cover removed,

l 1g. 4 is an enlarged transverse section and Fig. 5 is a plan showing the junction box for the leads with its cover removed.

The two thermal strips (1 a are arranged.

side by side and fixed at their ends to projections b on a box or casing c in which the are deflected towards the casing c and have separate plungers (Z d attached to them which pass through stuffing boxes e e into plate or slab g of insulating material provided with openings 9 for the passage of the plungers d d and supporting movable contacts h it carried on spring arms t i which are held against the inner ends of the respective o )erating plungers d (1. Any movement of t 16 thermal strips is thus communicated through their plungers d d to the spring arms i t and contacts h h which are arranged a short distance apart and in line with an adjustable screw stop 1 carried by a bracket 1 Both strips plunger (1. Both adjustingscrews 7' i are provided with adjustable dials 7c 7r and pointers so arranged that the contacts can be caused to close the circuit at any temperature indicated on the dials.

For the connection of the electrical leads m a box or chamber 0 is cast on or fixed to the casing c and provided with a detachable cover plate 0 held. in position by screws. 'lhe leads are held by the screws n n screwed into brass plates 0 o in a block of insulating material 2 in the chamber 0 Short flexible conductors not shown fixed by screws 0 0 to the plates 0 0 electrically connect the said plates with the contact screws 11 i and bracket y" through the blocks 0" 0.

The lid 0 of the casing c is tightly fixed by screws a layer of packing being interposed, and the box is fixed in position on a wall, ceiling or other support by a bracket 7. cast on the casing.

In operation the plungers d d which. are tipped with insulating material actuate the corresponding contacts h h the contact 72, operated by the less sensitive strip a moving in front of the contact h and thus preventing the alarm circuit being closed by ordinary temperature fluctuations due to atmospheric changes, artificial heating of buildings and the like. Should however the rise of temperature although gradual exceed a predeterinined amount the leading contact h is arrested by the sto j to enable the contact h to overtake it an close the circuit. stop y forms a contact the circuit is closed as soon as the moving contact it reaches it. A

Or if the r set to operate at lower temperatures than hitherto.

What Iclaim and desire to secure by Letters Patent is 1. An electric fire alarm apparatus comprising two thermal strips, one of which is more sensitive to changes in temperature than the other, and movable contacts operatively connected with said strips respectively and arranged to move in the same path in the same direction, and an adjustably fixed stop arranged in the path of the moving contacts. I

2. An electric fire alarm apparatus comprising a pair of thermal strips fixed at their ends and formed of different sensitiveness to changes of tem erature, plungers connected to the strips, e ectrical contact arms in the paths of the )lungers and su porting contacts arrange to move one be 1md the other in ap roximately the same path, an adg'ustable ixed stop or contact in the path 0'' the moving contacts, and a casing inclosing the contacts substantially as described.

3. A fire alarm apparatus comprising thermal strips of different sensitiveness to temperature changes, plungers connected with said strips and electrical contacts connected to move one in advance of the other in the paths of the plungers and of each other.

4. In a fire alarm apparatus, the combination of a casing, two thermal strips arranged side by side within said casing and one being less sensitive to changes in temperature than the other, plungers attached to said strips, spring members carrying contacts arranged in the paths of said plungers and of each other, an adjusting screw carried by one of said members and having a dial and moving in front of the other contact, and means for limiting the movement of the leading contact' In testimony whereof I have affixed my signature, in presence of two witnesses.

ALFRED HENRY MONEIL.

Witnesses ALFRED NUTTING, PERoY PHILLIPPS. 

